The present invention relates to a suspension arm for a vehicle wheel suspension having on one end a stub axle for receiving a wheel, and on another end a fastener for a bearing connecting to a vehicle subframe.
Providing vehicle wheel suspensions with intended breakpoints is described. For example, in European Patent Document EP 993 382 B1, which describes a four-point suspension arm of a rigid axle suspension for utility vehicles, which is connected as a torsionable cross via two joints on each side, having a distance to one another in the vehicle transverse direction, on one side to the vehicle axle and on the other side to the vehicle body. One of the four arms of the four-point suspension arm has an intended breakpoint, which is designed in such a way that in the event of axial strain well above the maximum demands to be expected and thus destruction of the four-point suspension arm possibly connected thereto, this destruction first occurs in the area of the intended breakpoint and thus controllably. It is thus intended that the vehicle may still drive to the closest service station without external support, because one of the two four-point suspension arms is still fastened to the vehicle axle.
The axial strain originates from the strain, i.e., overloading of the vehicle, in this case. For other axial strains, for example, in case of an accident, this intended breakpoint is not expedient. In addition, sharp open fracture surfaces, which may damage other components in the event of an accident, arise in the event of fracture of the suspension arm in this way.
The object of the present invention is to provide a suspension arm for a vehicle wheel suspension which deforms as little as possible even in the event of a severe accident and may thus favorably slide off of other vehicle components upon touching them. Therefore, as few sharp-edged, externally active fracture surfaces as possible are also to arise.
According to the present invention, a suspension arm for a vehicle wheel suspension, which is essentially provided on a first end with a stub axle for receiving a vehicle wheel and is essentially provided on at least one second end with a hole for receiving a fastener to fasten a bearing to connect the suspension arm to a subframe or vehicle body, the suspension arm having an intended breakpoint to fail because of strain overload due to deformation of the vehicle during an accident, is characterized in that the intended breakpoint is designed in such a way that the fastener breaks out of the hole.
It is advantageously ensured by such an intended breakpoint in the suspension arm that it deforms as little as possible even in the event of a severe accident and may thus favorably slide off of other vehicle components upon touching them. The suspension arm essentially maintains its form, so that no sharp-edged, externally active fracture surfaces arise.
In preferred embodiments of the present invention, the suspension arm is produced by a casting method, in particular from cast light alloy. If the fastener is a bolt or a screw, it may easily break at least partially out of the hole essentially in the radial direction, if its wall is previously weakened in at least one radial direction outward from the hole center point, in particular by at least one material recess.
In a further preferred embodiment of the present invention, the hole is a pocket threaded hole and the fastener is a screw which is screwed into the pocket threaded hole. The suspension arm having such a fastener may be produced very cost-effectively.
The suspension arm is advantageously free of sharp, externally active sharp-edged fracture surfaces in particular if the material recess in the suspension arm is made, particularly by a casting core, particularly as bag-shaped, in such a way that twisting or displacement of the suspension arm caused by an accident turns or pushes the fastener, in particular the screw, at least partially into the material recess while breaking through the wall of the hole.
The failure of the intended breakpoint may be advantageously implemented easily in that the particularly bag-shaped material recess is mechanically machined into the suspension arm in the direction toward the hole, in particular by removing material. The dimension of the wall of the hole, in the direction toward the material recess, is most simply determined by the material-removing machining of the material recess in the suspension arm.
If the suspension arm is a wheel suspension for a rear wheel, in the event of a rear impact, the advantages of the present invention are especially effective if the material recess runs essentially in the horizontal direction, having its opening oriented toward the vehicle exterior associated with the suspension arm, parallel and oriented identically to the hole, in particular situated behind the hole viewed in the travel direction.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.